Objective with pupil obscuration

ABSTRACT

In accordance with the present invention, a projection exposure apparatus includes an illuminating system to illuminate a drivable micromirror array and an objective which projects the drivable micromirror array onto the photosensitive substrate. The objective includes mirrors which are arranged coaxial with respect to a common optical axis. The objective can be a catoptric objective and can have a numerical aperture at the substrate greater than 0.1 and can have an imaging scale ratio of greater than 20:1. The objective can also include at least two partial objectives with an intermediate image plane between the at least two partial objectives and can consist of mirrors that are coated with reflecting layers which are adapted to reflect two mutually separated operating wavelengths.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/723,600, filed Nov. 21, 2003, now U.S. Pat. No. 6,894,834, which is acontinuation of International Application Serial No. PCT/EP02/09153,filed Aug. 16, 2002 and published in English on Feb. 27, 2003, which isstill pending, and which claims priority from German Patent ApplicationNo. 101 39 177.3, filed Aug. 16, 2001, all of which are herebyincorporated by reference in their entirety.

TECHNICAL FIELD

The invention relates to an objective with mirrors whose central mirrorapertures cause a pupil obscuration. An objective of the type consideredherein includes two partial objectives, the first partial objectiveprojecting a first field plane onto an intermediate image, and thesecond partial objective projecting the intermediate image onto a secondfield plane. Such objectives are used, for example, as projectionobjectives in microlithography or as inspection objectives for observingsurfaces, in particular wafer surfaces.

BACKGROUND

Catoptric reduction objectives with a pupil obscuration and intermediateimage for application in microlithographic projection exposure apparatusare disclosed in EP 0 267 766 A2. The exemplary embodiments shown inFIG. 2 and FIG. 3 of EP 0 267 766 A2 represent objectives with a firstpartial objective and a second partial objective. The two partialobjectives in the case of FIGS. 2 and 3 constitute two mutually opposingquasi-Schwarzschild objectives with different magnification ratios. Thequasi-Schwarzschild objectives are constructed from a convex and aconcave mirror which in each case have a central mirror aperture. In thecase of the objectives shown there, the aperture obscuration of 0.38 or0.33 is relatively large by comparison with the image-side numericalaperture of 0.3. Moreover, the objectives have only a magnificationratio of 0.6 or of 0.4. The numerical aperture at the intermediate imageis greater than in the image plane due to the configuration of the twomutually opposing quasi-Schwarzschild objectives.

A reflective projection objective for EUV (Extreme Ultraviolet)lithography with pupil obscuration, but without an intermediate image,is disclosed in U.S. Pat. No. 5,212,588. The projection objectiveincludes a convex mirror with a central mirror aperture, and a concavemirror with a central mirror aperture. The rays emanating from theobject plane are reflected four times at the two mirrors before theystrike the image plane. The image-side numerical aperture is onlybetween 0.08 and 0.3 in the case of an aperture obscuration of between0.4 and 0.7. The magnification ratio in the exemplary embodiments isbetween −0.3 and −0.2.

A further reflective projection objective for EUV lithography with pupilobscuration, but without an intermediate image, is disclosed in U.S.Pat. No. 5,003,567. In this case, the projection objective comprises apair of spherical mirrors which are coated with multilayers and have acommon center of curvature. In this case, the first mirror is a convexmirror, while the second mirror is a concave mirror. However, theseobjectives of the Schwarzschild type have a large image field curvature,and U.S. Pat. No. 5,003,567 therefore proposes applying thestructure-carrying mask (reticle) to a curved substrate.

Reflective projection objectives for EUV lithography with pupilobscuration and intermediate image are also disclosed in EP 1 093 021A2. The first partial objective, arranged between the object plane andthe intermediate image, has four or six mirrors which are insertedextra-axially except for the mirror arranged in the aperture plane. Thefirst partial objective does not lead to pupil obscuration in this case.The second partial objective includes a convex mirror with anextra-axial mirror aperture, and a concave mirror with an extra-axialmirror aperture. The mirror which lies geometrically closest to theimage plane is a convex mirror, and accordingly the thickness of themirror substrate is greatest on the optical axis. This leads to agreater aperture obscuration when the free image-side working distanceand the substrate thickness of the convex mirror are considered. Inaddition, convex mirrors generally have a lesser diameter than concavemirrors, since they have a diverging optical power. However, in the caseof a lesser mirror diameter, the mirror obscuration, that is to say theratio of the diameter of the mirror aperture to the diameter of themirror, is more unfavorable.

A catoptric microscope objective with pupil obscuration, but without anintermediate image, is disclosed in U.S. Pat. No. 4,863,253. It includesa convex mirror without a central mirror aperture, and a concave mirrorwith a central mirror aperture. In this arrangement, after reflection atthe concave mirror the rays do not pass through a mirror aperture in theconvex mirror, but are guided past the first mirror on the outside. Thisleads to a very high aperture obscuration by the convex mirror.

The publication entitled “Aplanatic corrector designs for the extremelylarge telescope” by Gil Moretto (Applied Optics; Vol. 39, No. 16; 1 Jun.2000; 2805–2812) discloses a mirror telescope which has, downstream of aspherical primary mirror, a correction objective which corrects thespherical aberration and coma caused by the primary mirror. In thiscase, the correction objective projects the intermediate image formed bythe primary mirror onto the image plane of the telescope enlarged with amagnification ratio of 3.5. The objective includes two concave mirrorswhich project the intermediate image onto a further intermediate image,and a pair of mirrors composed of a concave mirror and a convex mirrorwhich project the further intermediate image onto the image plane of thetelescope. The projection of the intermediate image formed by theprimary mirror onto the further intermediate image has a reduction ratioof −0.9, while the projection of the further intermediate image onto theimage plane of the telescope is enlarged with a magnification ratio of−3.75. The numerical aperture is 0.1 at the image plane of the telescopeand 0.345 at the intermediate image. Because of the mirror apertures,the objective has a pupil obscuration which is relatively large bycomparison with the numerical aperture. The correction objective alsohas a relatively large field curvature, since the convex mirror has onlya slight curvature.

A correction objective for a telescope is also disclosed in thepublication entitled “Optical design of the Hobby-Eberly Telescope FourMirror Spherical Aberration Corrector” by R. K. Jungquist (SPIE Vol.3779, 2–16, July 1999). The optical design is very similar to thepreviously described correction objective. It is exclusively concavemirrors that are used in the correction objective shown, and so thefield curvature is relatively large.

Controllable micromirror arrays are disclosed in the publicationentitled “Digital Micromirror Array for Projection TV” by M. A. Mignard(Solid State Technology, July 1994, pp. 63–68). Their use as object tobe projected in projection exposure apparatus forms the content ofpatents U.S. Pat. No. 5,523,193, U.S. Pat. No. 5,691,541, U.S. Pat. No.6,060,224 and U.S. Pat. No. 5,870,176. In the exemplary embodimentsdescribed there, the respective projection objective is, however,illustrated only diagrammatically. Concrete exemplary embodiments forprojection objectives which are adapted to the requirements of so-calledmaskless lithography are not contained in the patents.

A catadioptric projection objective with pupil obscuration andintermediate image is disclosed in DE 197 31 291 C2. In this case, theobjective has a refractive and a catadioptric partial objective, and isused in a wide UV wavelength region. In addition to lenses for colorcorrection, a concave mirror and an approximately plane mirror arearranged in the catadioptric partial objective. Because of the use oflenses, it is not possible to use this objective in the case of EUVwavelengths (<20 nm). The projection objective is used, for example, inan inspection system for observing wafer surfaces.

OBJECT OF THE INVENTION

It is an object of the invention to improve projecting objectives withpupil obscuration, in particular to reduce the aperture obscuration.

SUMMARY OF THE INVENTION

In accordance with the present invention, a projection exposureapparatus includes an illuminating system to illuminate a drivablemicromirror array and an objective which projects the drivablemicromirror array onto the photosensitive substrate. The objectiveincludes mirrors which are arranged coaxial with respect to a commonoptical axis.

The objective can be a catoptric objective and can have a numericalaperture at the substrate greater than 0.1.

In another aspect, a projection exposure apparatus according to thepresent invention includes an illuminating system to illuminate adrivable micromirror array and an objective, which projects the drivablemicromirror array onto a photosensitive substrate. The objective is acatoptric objective with an imaging scale ratio of greater than 20:1.

In yet another aspect, a projection exposure apparatus according to thepresent invention includes an illuminating system to illuminate adrivable micromirror array and an objective, which projects the drivablemicromirror array onto a photosensitive substrate. The objectiveincludes at least two partial objectives with an intermediate imageplane between the at least two partial objectives.

In addition, the objective can be an objective with pupil obscurationand can consist of mirrors that are coated with reflecting layers whichare adapted to reflect two mutually separated operating wavelengths.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed description of the invention follows below, makingreference to the drawings, wherein:

FIG. 1A represents a sectional view of a first exemplary embodiment ofthe invention;

FIG. 1B represents an enlarged detail of FIG. 1A;

FIG. 2A represents a sectional view of a second exemplary embodiment ofthe invention;

FIG. 2B represents an enlarged detail of FIG. 2A;

FIG. 3A represents a sectional view of a third exemplary embodiment ofthe invention;

FIG. 3B represents an enlarged detail of FIG. 3A;

FIG. 4 schematically illustrates a lithographic projection apparatuswith a controllable micromirror array;

FIG. 5 schematically illustrates a lithographic projection apparatuswith a structure-carrying mask; and

FIG. 6 schematically illustrates an inspection system.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

An objective according to the invention that meets the foregoingobjective includes a first partial objective and a second partialobjective which are arranged along an optical axis. The first partialobjective, which includes a first convex mirror with a first centralmirror aperture and a second concave mirror with a second central mirroraperture, projects a first field plane onto an intermediate image. Lightrays which emanate from the first field plane first pass through thesecond mirror aperture, are then reflected at the first mirror, nextreflected at the second mirror, and then pass through the first mirroraperture. Since the diameter of the second mirror aperture is decisivelydetermined by the diameter of the first mirror, it is advantageous forthe purpose of reducing the aperture obscuration to provide the firstmirror as convex mirror and the second mirror as concave mirror so thatthe first mirror has a substantially lesser diameter than the secondmirror.

The first mirror and the second mirror are arranged at a first axialdistance from each other. If not otherwise stated, in this applicationthe axial distance between two mirrors is determined between the surfacevertices of the two mirrors. In the case of mirrors with central mirrorapertures, the surface vertex specifies the point on the optical axis atwhich the mirror surface would intersect the optical axis if the mirrorhad no mirror aperture. The second mirror has a second axial distancefrom the intermediate image. The location of the intermediate image isgiven by the paraxial position of the intermediate image. In order tokeep the aperture obscuration as low as possible, the ratio of firstaxial distance to second axial distance has a value of between 0.95 and1.05, in particular between 0.98 and 1.02. In this case, theintermediate image is located at least approximately at the location ofthe first mirror. Since the diameter of a ray pencil is minimal in fieldplanes, and the pencil diameter is determined by the diameter of amirror aperture on the other hand, it is advantageous to place theintermediate image as close as possible to the location of the firstmirror. The intermediate image can therefore also be located, forexample, between the first mirror and the second mirror, at the surfacevertex of the first mirror or downstream of the surface vertex of thefirst mirror in the direction of the light, in which case the axialdistances should conform to the above-mentioned condition.

The intermediate image is projected onto a second field plane by meansof the second partial objective. This has the purpose of providingbetween the optical components of the second partial objective and thesecond field plane a sufficiently large free optical working distance,which does not exist between the intermediate image and the opticalcomponents of the first partial objective. The second partial objectivehas a third concave mirror with a third central mirror aperture and afourth concave mirror with a fourth central mirror aperture, which arearranged facing one another. In this case, light rays first pass throughthe fourth mirror aperture, are reflected at the third mirror, aresubsequently reflected at the fourth mirror, and then pass through thethird mirror aperture. In order to keep the aperture obscuration as lowas possible, the third mirror is arranged as close to the second fieldplane as is allowed by the free optical working distance. In addition,the third mirror is a concave mirror with a relatively large diameter,and thus the ratio of the diameter of the mirror aperture to thediameter of the mirror assumes smaller values. The axial distancebetween the third mirror and the second field plane is denoted below byZ_(M3-IM). The distance Z_(M3-IM) advantageously has a minimum valuewhich is equal to the sum of the minimum substrate thickness of thethird mirror and a minimum free optical working distance. The minimumsubstrate thickness is specified on the optical axis between the surfacevertex and the rear surface even if, because of the central mirroraperture, the mirror has no substrate material there. The minimumsubstrate thickness is 3% of the diameter of the mirror. Since it is aconcave mirror, the physically present substrate thickness of the thirdmirror is greater. If the aperture obscuration so permits, it isadvantageous when the minimum substrate thickness on the axis is 5% oreven 10% of the diameter of a concave mirror with central mirroraperture. The minimum free optical working distance between the rearsurface of the third mirror and the second field plane is 5.0 mm. Thisfree optical working distance ensures the positioning of an object inthe second field plane. The maximum value of the distance Z_(M3-IM) isprimarily a function of the tolerable aperture obscuration and secondlyof the numerical aperture NA in the second field plane. It isadvantageous for a low aperture obscuration when the diameter of thethird mirror aperture is smaller than 50% of the diameter Du_(M3) of thethird mirror. Since the diameter of the third mirror aperture increaseslinearly with the tangent of the arcsine of the numerical aperture inthe second field plane, and with the distance of the third mirror fromthe field plane, the maximum value of the distance Z_(M3-IM) is given bythe following relationship:

$Z_{{M3} - {IM}}^{\max} = {\frac{0.25 \cdot {Du}_{M3}}{\tan\left( {\arcsin({NA})} \right)}.}$

In order to be able to use the objective for projecting an extendedobject onto an image in a projection exposure apparatus or in aninspection system, for example, the field curvature of the objectiveshould be corrected as well as possible. The objective advantageouslyhas a Petzval radius whose absolute value is greater than the axialdistance between the first and second field planes. In order tocompensate for the positive contributions of the concave mirrors to thePetzval sum, the first convex mirror supplies a large negativecontribution. Since the first convex mirror therefore has a largenegative optical power and thus, by comparison with the concave mirrors,a small diameter, this mirror is particularly critical with regard toits contribution to the aperture obscuration. However, since it isarranged at least approximately at the location of the intermediateimage, the objective has a low aperture obscuration despite a goodPetzval correction.

Only light rays with aperture angles starting from a specific minimumvalue contribute to the projection in this objective with pupilobscuration. The aperture angles are measured with reference to theoptical axis. The minimum aperture angle results for the light ray whichis still transmitted by all mirrors and not vignetted by a mirroraperture. The light rays are not directly vignetted by the mirrorapertures, but pass as false light through the latter and strike aspecial light blocking device, while the remaining rays of a ray pencilwith larger aperture angles are reflected by the mirrors. The apertureobscuration is defined as the ratio of the sine of the minimum apertureangle in the second field plane to the numerical aperture in the secondfield plane. Values of less than 0.6, in particular less than 0.5, canbe achieved for the aperture obscuration by means of the arrangement ofthe intermediate image in the vicinity of the first mirror, and with theuse of a concave mirror in the vicinity of the second field plane.

In addition to a low aperture obscuration, a large value for the ratioof the numerical aperture in the second field plane to the apertureobscuration is also an important feature of the objective. The largerthe numerical aperture of the objective in the second field plane, themore difficult it is to achieve a low aperture obscuration. Theobjective is distinguished in that this ratio is greater than 1.2, inparticular greater than 1.5.

The numerical aperture in the second field plane is greater than 0.3, inparticular greater than 0.4, with particular preference greater than0.6.

Between the first field plane and the second field plane, the objectivehas an imaging ratio of greater than 4:1, in particular greater than10:1, with particular preference greater than 20:1. Imaging ratio ofbetween 4:1 and 10:1 are typical for projection objectives forlithography. Imaging ratio of greater than 20:1 are of interest, forexample, for microscope objectives, inspection objectives or projectionobjectives which project a controllable micromirror array onto aphotosensitive substrate. In this context, the imaging ratio between twoconjugated field planes is defined as the absolute value of the ratiobetween an object height and an image height, wherein the magnificationratio between two conjugated field planes is defined as the ratiobetween an image height and an object height, having e.g. a positivesign for an upright image and a negative sign for an inverted image.

Since the objective includes two partial objectives, it is advantageouswhen both the imaging ratio between the first field plane and the secondfield plane and also the imaging ratio between the intermediate imageand the second field plane are greater than 1:1, in particular greaterthan 1.1:1. As a result, the numerical aperture between the first fieldplane and the second field plane is increased step-by-step. The maximumnumerical aperture therefore does not occur until in the second fieldplane.

In order to keep the aperture obscuration as low as possible, it isadvantageous if, between the first field plane and the intermediateimage, the first partial objective has an imaging ratio which issubstantially greater by comparison with the second partial objective.Thus, this imaging ratio should be greater than 3:1, in particulargreater than 5:1, with particular preference greater than 10:1.

Due to the negative optical power of the first mirror, it is possible tomake the diameter of the second mirror substantially larger than thediameter of the first mirror. The ratio of the diameter of the secondmirror to the diameter of the first mirror should be greater than 3:1,in particular greater than 5:1. Since the diameter of the mirroraperture of the second mirror is approximately equal to the diameter ofthe first mirror, the second mirror leads only to a low apertureobscuration, or to no increase in the aperture obscuration, which iscaused by the other mirrors.

Since the pencil cross section of the light rays is smallest in theregion of the intermediate image, and thus also in the region of thefirst mirror, it is advantageous to arrange the fourth mirror in theregion of the intermediate image, or in the region of the first mirror.The axial distance between the fourth mirror and the first mirror shouldbe less than 10% of the axial distance of the first field plane from thesecond field plane. Unless otherwise stated, dimensions in thisapplication are given not in absolute terms, but are stated as ratiosrelative to the axial distance between the first and second fieldplanes, since all dimensions can be scaled up or down proportionallywith this distance. In this case, it can be advantageous to arrange thefirst mirror in the mirror aperture of the fourth mirror. The twomirrors can also have the same mirror substrate, with the mirror surfaceof the first mirror on the front surface of the mirror substrate, andthe mirror surface of the fourth mirror on the rear surface of themirror substrate.

In an advantageous embodiment, the previously described features areachieved with only four mirrors.

In order to be able to increase the numerical aperture between the firstfield plane and the second field plane in two steps, a furtherintermediate image is advantageously arranged between the intermediateimage and the second field plane. For this purpose, a fifth mirror witha fifth central mirror aperture and a sixth mirror with a sixth centralmirror aperture are arranged optically between the intermediate imageand the further intermediate image. The light rays first pass throughthe sixth mirror aperture, are reflected at the fifth mirror, arereflected at the sixth mirror, and then pass through the fifth mirroraperture. The third mirror and the fourth mirror are located opticallybetween the further intermediate image and the second field plane. Thesecond partial objective therefore has two subsystems, the firstsubsystem comprising the optical components between the intermediateimage and the further intermediate image, in particular the fifth mirrorand the sixth mirror, and the second subsystem comprising the opticalcomponents between the further intermediate image and the second fieldplane, in particular the third mirror and the fourth mirror.

When the fifth mirror and the sixth mirror are concave mirrors, they canhave relatively large diameters by comparison with the mirror apertures.Thus, they worsen the aperture obscuration only slightly, if at all. Asconcave mirrors, they are arranged facing one another.

As an alternative possibility, the fifth mirror can be a convex mirrorand the sixth mirror a concave mirror. In this case, the fifth mirrorand the sixth mirror have an arrangement similar to the first mirror andthe second mirror.

In order for the ray pencil coming from the sixth mirror to have a smallray diameter at the fifth mirror, and thus also for the fifth mirroraperture to have only a small diameter, it is advantageous if thedistance of the further intermediate image from the fifth mirror is lessthan 5% of the axial distance of the first field plane from the secondfield plane.

Since the numerical aperture at the intermediate image is substantiallygreater than in the first field plane, the sixth mirror should bearranged close to the intermediate image, or close to the first mirror.The axial distance of the sixth mirror from the first mirror isadvantageously less than 10% of the axial distance of the first fieldplane from the second field plane.

For the same reason, the fourth mirror should be arranged close to thefurther intermediate image, or close to the fifth mirror. The axialdistance of the fourth mirror and the fifth mirror is advantageouslyless than 10% of the axial distance of the first field plane from thesecond field plane.

With the arrangement of at least six mirrors, in particular exactly sixmirrors, it is possible to achieve in the second field plane a numericalaperture greater than 0.6, in particular greater than 0.8 in conjunctionwith an aperture obscuration of less than 0.5.

If the object to be projected is a reflective object, the illuminatinglight must be introduced between the first field plane and the opticalcomponents of the first partial objective. Precisely in the case of EUVwavelengths of less than 20 nm, it is advantageous to use a so-calledgrazing-incidence mirror to introduce the illuminating light, where theangle of incidence for the light rays is more than 70° (measured fromthe normal vector of the mirror surface). A sufficiently large freeworking distance upstream of the first field plane is, however,necessary for such mirrors. This free working distance is advantageouslygreater than 20% of the axial distance between the first and secondfield planes.

With the objective of the foregoing description, it is possible tocorrect the projection for a field with a diameter of greater than 1.0mm in the second field plane.

In particular, the ratio between the spherical aberration and the axialdistance between the first and second field planes is less than 10⁻⁵.The value of the spherical aberration represents the third-orderspherical aberration according to the Seidel theory, i.e., the lateralaberration as calculated, for example, by the commercially availableoptical design software CodeV.

To use the objective as a projection objective or as an inspectionobjective, it is advantageous if the axial distance of the first fieldplane from the second field plane is at most 3000 mm.

If the objective has only mirrors, its application is not limited to aspecific range of wavelengths. Rather, it is possible by means of anappropriate coating of the mirrors to adapt the objective to thewavelength that is being used. The objective can also be usedsimultaneously at two separated operating wavelengths if the reflectivecoatings allow this. In the case of projection objectives of alithographic projection exposure apparatus, the projection can beperformed, for example, at a first wavelength, and the alignment ofstructure-carrying mask (reticle) and photosensitive substrate (wafer)can be performed at a second wavelength. It is advantageous to use theobjective at wavelengths of less than 200 nm, since in the case of thesewavelengths only a few transparent materials such as, for example,fluoride crystals are available. The use of mirrors is mandatory in thecase of wavelengths of less than 20 nm. At an operating wavelength ofapproximately 11 nm–13 nm, for example, mirrors with reflectivemultilayer coatings of molybdenum and silicon, or molybdenum andberyllium are used.

The application of the concept is not limited to purely reflectiveobjectives. It is also possible to arrange lenses between the individualmirrors, particularly in the region of the field planes and in theregion of an intermediate image. These lenses can be used, for example,to perform the color correction or to set the telecentricity.

In a preferred embodiment, the objective has a magnification ratio withan absolute value of less than 1.0. In this case, the projection of anobject in the first field plane produces a reduced image in the secondfield plane.

Such objectives are used, for example, as projection objectives inlithographic projection exposure apparatus. In a lithographic projectionexposure apparatus, an illuminating system illuminates astructure-carrying mask (reticle) which is projected by the projectionobjective onto a photosensitive substrate.

Such lithographic projection exposure apparatus are adequately knownfrom the prior art, being disclosed, for example, for EUV lithography inU.S. Pat. No. 5,212,588, U.S. Pat. No. 5,003,567 or EP 1 093 021 A2,whose content is incorporated herein by reference.

Microstructured semiconductor components are fabricated in amultiplicity of individual, very complex method steps. An importantmethod step relates to the exposure of photosensitive substrates(wafers), for example silicon substrates provided with photoresist. Inthis case, the reticular structure of the mask is projected onto thewafer by the projection objective during fabrication of a singleso-called layer.

It is also possible to use a controllable micromirror array instead of areticle in a lithographic projection exposure apparatus. Suchlithographic projection exposure apparatus are adequately known from theprior art, being disclosed, for example, in U.S. Pat. No. 5,523,193,U.S. Pat. No. 5,691,541, U.S. Pat. No. 6,060,224 and U.S. Pat. No.5,870,176, whose content is incorporated herein by reference. Since thepreviously described objectives permit an imaging ratio of greater than20:1 between the controllable micromirror array and a photosensitivesubstrate, the images of the individual micromirrors, whose size is ofthe order 1 μm, have dimensions of less that 50 nm. Consequently,controllable micromirror arrays also are of interest formicrolithography, since it is possible to implement resolutions of lessthan 100 nm.

In the fabrication of a single layer of a micro-structured semiconductorcomponent, the positions of the micromirrors are controlled inaccordance with a prescribed pattern in such a way that only the raypencils of those micromirrors which are to be projected are aimed intothe entrance pupil of the objective. All other ray pencils are preventedfrom contributing to the projection by a suitable ray trap.

It should be noted that the objective according to the invention is notrestricted to one sense of direction of the light path, but can also beused in an arrangement where the light rays emanate from the secondfield plane and a projected image is produced in the first field plane.In a preferred embodiment of this concept, the objective has amagnification ratio whose absolute value is greater than 1.0. In thiscase, an object arranged in the second field plane is projected into thefirst field plane to produce an enlarged image.

Such objectives are used, for example, as inspection objectives in aninspection system for observing a surface of an object. The surface ofthe object, in particular the surface of a wafer, is projected by theinspection objective with a large magnification ratio onto the entrysurface of an observation unit. The inspection system has anilluminating system which illuminates the surface directly or throughthe inspection objective. In the latter case, the illuminating light is,for example, introduced into the projecting beam path between the entrysurface of the observation unit and the inspection objective, or insidethe inspection objective. The light reflected by the wafer surface isevaluated according to various criteria by means of the observationunit.

Such inspection systems are adequately known from the prior art, beingdisclosed, for example, for the UV wavelength region in DE 197 31 291C2, whose content is incorporated herein by reference.

In addition to the application as projection objective or as inspectionobjective, the objective according to the invention can also be used inother optical arrangements where a diffraction-limited projection is tobe achieved in conjunction with very large numerical apertures,particularly in the case of EUV wavelengths. Microscopy, in particular,offers a wide field of applications.

FIG. 1A illustrates a first exemplary embodiment for an objective 1 inaccordance with the invention. A detail view without the large freeworking space on the object side is presented in FIG. 1B for the purposeof a clearer illustration. The optical data for the first exemplaryembodiment are listed in Table 1 in the format of the optical designsoftware CodeV.

The objective 1 includes the first partial objective 3 and the secondpartial objective 5, which are centered about the optical axis OA. Theobjective 1 projects the first field plane 7 with an imaging ratio of100:1 onto the second field plane 9. The numerical aperture NA in thesecond field plane 9 is 0.7. The diameter of the field in the secondfield plane 9 is 2 mm. The axial distance between the first field plane7 and the second field plane 9 is 2000 mm.

The first partial objective 3 projects the first field plane 7 with animaging ratio of 74:1 onto the intermediate image 11. It includes theconvex mirror 13 with the central mirror aperture 15, and the concavemirror 17 with the central mirror aperture 19. The concave mirror 17 isdesigned in such a way that the intermediate image 11 is formed in thevicinity of the convex mirror 13. The axial distance between the mirror17 and the paraxial position of the intermediate image 11 is equal tothe axial distance between the mirror 17 and the mirror 13 and is 68.8mm. The ratio of the diameter of the concave mirror 17 to the diameterof the convex mirror 13 is 3.0:1. The free optical working distancebetween the first field plane 7 and the mirror 17 is 1580 mm, assuming asubstrate thickness of 35.2 mm on the optical axis for the mirror 17.

The second partial objective 5 projects the intermediate image 11 ontothe second field plane 9 with an imaging ratio of 1.35:1. It includesthe concave mirror 21 with the central mirror aperture 23, and theconcave mirror 25 with the central mirror aperture 27. The mirror 21 isarranged close to the second field plane 9 and has an axial distance of40.0 mm from this plane. The mirror 21 has a diameter of 315.8 mm.Consequently, it should have a substrate thickness of 9.5 mm, at leaston the optical axis OA. The substrate thickness of the mirror 21 on theoptical axis is 30 mm. The difference between the substrate thicknessand the axial distance of the mirror 21 from the second field plane 9represents the free optical working distance, which is 10.0 mm in thefirst exemplary embodiment. On the other hand, the mirror 21 is arrangedso close to the second field plane 9 that the mirror obscuration is only0.3 in the case of a numerical aperture NA=0.7 in the second field plane9. The mirror obscuration is represented by the ratio of the diameter ofthe mirror aperture 23 to the diameter of the mirror 21. So that theconcave mirror 25 does not worsen the aperture obscuration, it isarranged in the vicinity of the convex mirror 13, or of the intermediateimage 11. The axial distance between the concave mirror 25 and theconvex mirror 13 is 71.3 mm.

Located between the concave mirror 21 and the concave mirror 25 is theaperture plane 29 and the light blocking device 31, which is designed asa ray trap. The diameter of the light blocking device 31 is fixed insuch a way that the ray pencils occurring in the second field plane 9have an aperture obscuration almost independent of field height. If amechanical shutter diaphragm with variable diameter is arranged in theaperture plane 29, the shutter blades can move on a curved surface inaccordance with the curvature of the aperture plane. It is also possibleto provide a plurality of flat mechanical diaphragms with variablediameter which can be inserted if required axially offset. The marginalrays 37 and 39, which emanate from the two field points 33 and 35 in thefirst field plane 7, go through the upper and lower margins of theaperture plane 29. The field point 33 is located on the optical axis OA,and the field point 35 is located on the upper margin of the field at adistance of 100 mm from the optical axis OA. Further illustrated for thefield point 33 are the rays 41 which are just no longer vignetted by themirror apertures. In the second field plane 9, they have an apertureangle of 18.4°, and so the aperture obscuration is 0.45. The ratio ofthe numerical aperture in the second field plane to the apertureobscuration is therefore 1.56. The mirror aperture 19 of the concavemirror 17 acts in a limiting fashion for the aperture obscuration in thefirst exemplary embodiment.

It was possible in the first exemplary embodiment largely to correct thefield curvature by means of the negative optical power of the convexmirror 13. The Petzval radius is 192137 mm.

It was possible in the first exemplary embodiment to correct thethird-order spherical aberration to a value of 0.6 μm.

A second exemplary embodiment of an objective 201 in accordance with theinvention is illustrated in FIG. 2A. FIG. 2B shows a detail from FIG. 2Afor the purpose of better illustration. The optical data for the secondexemplary embodiment are specified in Table 2 in the format of theoptical design software CodeV. The elements in FIG. 2A/B whichcorrespond to the elements of FIG. 1A/B have the same reference symbolsas in FIG. 1A/B increased by the number 200. Reference is made to thedescription relating to FIG. 1A/B for a description of these elements.

The objective 201 includes the first partial objective 203 and thesecond partial objective 205, which are arranged centered about theoptical axis OA. The objective 201 projects the first field plane 207with an imaging ratio of 100:1 onto the second field plane 209. Thenumerical aperture NA in the second field plane 209 is 0.9. The diameterof the field in the second field plane 209 is 2 mm. The axial distancebetween the first field plane 207 and the second field plane 209 is 2000mm.

The first partial objective 203 projects the first field plane 207 withan imaging ratio of 52:1 onto the intermediate image 211. It includesthe convex mirror 213 with the central mirror aperture 215, and theconcave mirror 217 with the central mirror aperture 219. The concavemirror 217 is designed in such a way that the intermediate image 211 isformed in the vicinity of the convex mirror 213. The axial distancebetween the mirror 217 and the paraxial position of the intermediateimage 211 is equal to the axial distance between the mirror 217 and themirror 213 and is 447.5 mm. The ratio of the diameter of the concavemirror 217 to the diameter of the convex mirror 213 is 14.4:1. The freeoptical working distance between the first field plane 207 and themirror 217 is 1050 mm, assuming a substrate thickness of 36.4 mm on theoptical axis OA for the mirror 217.

The second partial objective 205 projects the intermediate image 211onto the second field plane 209 with an imaging ratio of 1.9:1. Theprojection is performed via an intermediate projection of theintermediate image 211 onto the further intermediate image 243. Theintermediate image 211 is projected by the concave mirror 245 with thecentral mirror aperture 247, and by the concave mirror 249 with thecentral mirror aperture 251, onto the further intermediate image 243which is projected, in turn, by the concave mirror 221 with the centralmirror aperture 223, and by the concave mirror 225 with the centralmirror aperture 227, onto the second field plane 209. It is possible bymeans of this further intermediate projection to increase the numericalaperture in the field planes step by step such that it was finallypossible to achieve a numerical aperture of 0.9 in the second fieldplane 209.

In order to keep the aperture obscuration as low as possible, themirrors in the second partial objective 205 are arranged geometricallyin the vicinity of field planes in each case. The optical power of theconcave mirror 249 is designed in such a way that the furtherintermediate image 243 is formed in the vicinity of the concave mirror245. The axial distance between the mirror 249 and the paraxial positionof the further intermediate image 243 is equal to the axial distancebetween the mirror 249 and the mirror 245, and is 60.6 mm.

In order to keep the aperture obscuration as low as possible, theconcave mirrors 249 and 225 are arranged in the vicinity of theintermediate image 211, or of the further intermediate image 243. Theaxial distance between the concave mirror 249 and the intermediate image211 is 50.0 mm, and likewise 50.0 mm between the concave mirror 225 andthe further intermediate image 243. These axial distances alsocorrespond in each case to the axial distances in relation to the mirror213, or to the mirror 245. The axial distances are selected to be largeenough to accommodate the adjacent mirrors 213 and 249, or 245 and 225,with an axial distance of the mirror rear surfaces, taking account ofthe respective substrate thickness. The substrate of mirror 245 does nothave a plane rear surface. In order for the rays passing through themirror aperture 247 not to be vignetted at the substrate, the rearsurface has a frustoconical depression surrounding the central mirroraperture 247.

The mirror 221 is arranged close to the second field plane 209 and hasan axial distance of 40.0 mm from this plane. The mirror 221 has adiameter of 748.2 mm. Consequently, it should have a substrate thicknessof 22.4 mm, at least on the optical axis OA. The substrate thickness ofthe mirror 221 on the optical axis is 34 mm. The difference between thesubstrate thickness and the axial distance of the mirror 221 from thesecond field plane 209 represents the free optical working distance,which is 6.0 mm in the second exemplary embodiment. On the other hand,the mirror 221 is arranged close enough to the second field plane 209that the mirror obscuration is only 0.27 with a numerical apertureNA=0.9 in the second field plane 209.

The aperture plane 229 with the light blocking device 231 is locatedbetween the concave mirror 221 and the concave mirror 225. The marginalrays 237 and 239, which emanate from the two field points 233 and 235 inthe first field plane 207, go through the upper and lower margins of theaperture plane 229. The field point 233 is located on the optical axisOA, and the field point 235 is located on the upper margin of the fieldat a distance of 100 mm from the optical axis OA. The apertureobscuration is 0.43 in the second exemplary embodiment. The ratio of thenumerical aperture in the second field plane to the aperture obscurationis therefore 2.09. The mirror aperture 251 of the concave mirror 249 isthe limiting factor for the aperture obscuration in the second exemplaryembodiment.

It was possible in the second exemplary embodiment largely to correctthe field curvature by means of the negative optical power of the convexmirror 213. The Petzval radius is 8940 mm.

It was possible in the second exemplary embodiment to correct thethird-order spherical aberration to a value of 0.8 μm.

A third exemplary embodiment of an objective 301 in accordance with theinvention is illustrated in FIG. 3A. FIG. 3B shows a detail from FIG. 3Afor the purpose of better illustration. The optical data for the thirdexemplary embodiment are specified in Table 3 in the format of theoptical design software CodeV. The elements in FIG. 3A/B whichcorrespond to the elements of FIG. 2A/B have the same reference symbolsas in FIG. 2A/B increased by the number 100. Reference is made to thedescription relating to FIG. 2A/B for a description of these elements.

The objective 301 includes the first partial objective 303 and thesecond partial objective 305, which are centered on the optical axis OA.The objective 301 projects the first field plane 307 with an imagingratio of 100:1 onto the second field plane 309. The numerical apertureNA in the second field plane 309 is 0.9. The diameter of the field inthe second field plane 309 is 2 mm. The axial distance between the firstfield plane 307 and the second field plane 309 is 2389 mm.

The first partial objective 303 projects the first field plane 307 withan imaging ratio of 66:1 onto the intermediate image 311. It includesthe convex mirror 313 with the central mirror aperture 315, and theconcave mirror 317 with the central mirror aperture 319. The concavemirror 317 is designed in such a way that the intermediate image 311 isformed in the vicinity of the convex mirror 313. The axial distancebetween the mirror 317 and the paraxial position of the intermediateimage 311 is equal to the axial distance between the mirror 317 and themirror 313 and is 450.8 mm. The ratio of the diameter of the concavemirror 317 to the diameter of the convex mirror 313 is 14.9:1. The freeoptical working distance between the first field plane 307 and themirror 317 is 1470 mm, assuming a substrate thickness of 33.3 mm on theoptical axis OA for the mirror 317.

The second partial objective 305 projects the intermediate image 311onto the second field plane 309 with an imaging ratio of 1.5:1. Theprojection is performed via an intermediate projection of theintermediate image 311 onto the further intermediate image 343. Theintermediate image 311 is projected by the concave mirror 345 with thecentral mirror aperture 347, and by the concave mirror 349 with thecentral mirror aperture 351, onto the further intermediate image 343which is projected, in turn, by the concave mirror 321 with the centralmirror aperture 323, and by the concave mirror 325 with the centralmirror aperture 327, onto the second field plane 309.

The mirrors in the second partial objective 305 are respectivelyarranged in the vicinity of field planes. The optical power of theconcave mirror 349 is designed in such a way that the furtherintermediate image 343 is formed in the vicinity of the concave mirror345. The axial distance between the mirror 349 and the paraxial positionof the further intermediate image 343 is equal to the axial distancebetween the mirror 349 and the mirror 345, and is 68.9 mm.

The concave mirrors 349 and 325 are arranged in the vicinity of theintermediate image 311, or of the further intermediate image 343. Theaxial distance between the concave mirror 349 and the intermediate image311 is 18.9 mm, while that between the concave mirror 325 and thefurther intermediate image 343 is 37.5 mm. These axial distances alsocorrespond in each case to the axial distances in relation to the mirror313, or to the mirror 345. In the third exemplary embodiment, the axialdistances between the mirrors 311 and 349, or between the mirrors 345and 325, are smaller than the sum of the respective mirror substrates.Thus, by contrast with the second exemplary embodiment, the mirror 311is located in the mirror aperture 351 of the mirror 349, and the mirror345 is located in the mirror aperture 327 of the mirror 325. Whereas themirror 349 determines the aperture obscuration in the second exemplaryembodiment, the corresponding mirror 349 is no longer critical in thethird exemplary embodiment. The substrate rear surfaces of the mirrors313, 349 and 345 are not plane. In order that the rays passing throughthe mirror apertures are not vignetted on the mirror substrates, therear surfaces have frustoconical depressions surrounding the centralmirror apertures.

The mirror 321 is arranged close to the second field plane 309 and hasan axial distance of 40.0 mm from this plane. The mirror 321 has adiameter of 760.7 mm. Consequently, it should have a substrate thicknessof at least 22.8 mm on the optical axis OA. The substrate thickness ofthe mirror 321 on the optical axis is 35 mm. The difference between thesubstrate thickness and the axial distance of the mirror 321 from thesecond field plane 309 represents the free optical working distance,which is 5.0 mm in the third exemplary embodiment. On the other hand,the mirror 321 is arranged so close to the second field plane 309 thatthe mirror obscuration of the mirror 321 is only 0.26 in the case of anumerical aperture NA=0.9 in the second field plane 309.

The aperture plane 329 with the light blocking device 331 is locatedbetween the concave mirror 321 and the concave mirror 325. The marginalrays 337 and 339, which emanate from the two field points 333 and 335 inthe first field plane 307, go through the upper and lower margins of theaperture plane 329. The field point 333 is located on the optical axisOA, and the field point 335 is located on the upper margin of the fieldat a distance of 100 mm from the optical axis OA. The apertureobscuration is 0.39 in the third exemplary embodiment. The ratio of thenumerical aperture in the second field plane to the aperture obscurationis therefore 2.31. The mirror aperture 327 of the concave mirror 325acts in a limiting fashion for the aperture obscuration in the thirdexemplary embodiment.

It was possible in the third exemplary embodiment largely to correct thefield curvature by means of the negative optical power of the convexmirror 313. The Petzval radius is 76472 mm.

It was possible in the third exemplary embodiment to correct thespherical aberration of third order to a value of 0.3 μm.

A lithographic projection exposure apparatus 453 for EUV lithography isillustrated schematically in FIG. 4. A laser-induced plasma source 459serves as light source. In this case, a Xenon target, for example, isexcited by means of a pump laser 457 to emit EUV radiation. Theilluminating system 455 includes the collector mirror 461, thehomogenizing and field-forming unit 463 and the field mirror 465. Suchilluminating systems are described, for example, in U.S. Pat. No.6,198,793 (DE 199 03 807), which is owned by the same assignee as thepresent invention and whose content is incorporated herein by reference.The illuminating system 455 illuminates a restricted field on themicromirror array 467, which is arranged on the holding and positioningunit 469. The micromirror array 467 has 1000×1000 separatelycontrollable mirrors of size 10 μm×10 μm. Taking account of a minimumdistance of 0.5 μm between the micromirrors, the illuminating system 455should illuminate a square field of size 10.5 mm×10.5 mm. Themicromirror array 467 is located in the object plane of a projectionobjective 401, which projects the illuminated field onto aphotosensitive substrate 471. The photosensitive substrate 471 isarranged on the holding and positioning unit 473, which also permitsscanning of the micromirror array 467. One of the exemplary embodimentsillustrated in FIGS. 1 to 3 can be used as projection objective 401. Themicromirror array 467 is arranged in the first field plane, and thephotosensitive substrate 471 in the second field plane. In order for thefield mirror 465 not to vignette the projecting beam path, the fieldmirror 465 must be arranged at a sufficiently large distance from themicromirror array 467. On the other hand, this requires the illuminatedfield to be arranged not centered relative to the optical axis OA, butoutside the optical axis. Since, however, the object fields of theexemplary embodiments shown have a diameter of 200 mm, the illuminatedfield can be arranged, for example, at a distance of 70 mm from theoptical axis OA. The individual micromirrors of the micromirror array467 are projected onto the photosensitive substrate 471 with an imagingratio of 100:1, and so the images of the micromirrors have a size of 100nm. Consequently, it is possible to produce structures with a resolutionof approximately 100 nm on an image field of size 105 μm×105 μm, sincethe projection of the projection objective 401 is diffraction limited.By stepwise displacement and/or scanning of the photosensitive substrate471 by means of the holding and positioning unit 473, it is alsopossible to expose fields with dimensions of several millimeters. Thelithographic projection exposure apparatus 453 also has the ray trap475. This absorbs the light rays of those ray pencils which are notaimed into the entrance pupil of the projection objective 401 by themicromirrors. The computer and control unit 477 is used to control thepump laser 457, the illuminating system 455, for the purpose of varyingthe pupil illumination, the controllable micromirror array 467 and theholding and positioning units 473 and 469.

A further exemplary embodiment of a lithographic projection exposureapparatus 553 is illustrated in FIG. 5. The lithographic projectionexposure apparatus 553 has a reflective reticle 579 instead of thecontrollable micromirror array 467. The elements in FIG. 5 whichcorrespond to the elements of FIG. 4 have the same reference numerals asin FIG. 4 increased by the number 100. Reference may be made to thedescription relating to FIG. 4 for a description of these elements.Since the structures on the reflective reticle 579 can have dimensionsof less than 1 μm, it is possible to produce structures with resolutionsof less than approximately 10 nm on the photosensitive substrate 571,since the projection of the projection objective 501 is diffractionlimited.

An inspection system 681 for observing wafer surfaces is illustratedschematically in FIG. 6. An excimer laser 685 which produces light witha wavelength of 157 nm serves as light source. The illuminating system683 includes the homogenizing and field-forming unit 687 and the beamsplitter 689, for example a semitransparent mirror. The beam splitter689 couples the illuminating light into the inspection objective 601,which projects the surface of the object 691 to be analyzed onto theentry surface 693 of an observation unit 695. The object 691 is arrangedon an object stage 697 which permits the displacement and rotation ofthe object 691. One of the exemplary embodiments illustrated in FIGS. 1to 3 can be used as inspection objective 601. The object 691 is arrangedin the second field plane, and the entry surface 693 in the first fieldplane. It is possible, for example, to use the inspection objective 601to analyze a surface of 500 μm×500 μm. The image corresponding to thisobject field has dimensions of 50 mm×50 mm on the entry surface 693 ofthe observation unit 695. The computer and control unit 699 is used tocontrol the light source 685, the illuminating system 687, for thepurpose of varying the pupil illumination, and the object stage 697, andto evaluate the measured data from the observation unit 695. Using aninspection objective in accordance with the exemplary embodiments 1 to 3has the advantage that it is possible by means of an appropriate coatingof the mirrors to adapt the inspection objective to any wavelength, orto a wide wavelength range. In particular, the inspection objective canalso be used at EUV wavelengths of less than 20 nm.

TABLE 1 Optical Data for Objective of FIG. 1A/1B Element CurvatureRadius Aperture Diameter (Ref. Symbol) Front Back Thickness Front BackGlass Object inf. 1684.0346 Mirror 1 (13) A(1) −68.8152 C-1 reflectingMirror 2 (17) A(2) 344.7808 C-2 reflecting Mirror 3 (21) A(3) −62.6453C-3 reflecting APERTURE STOP 338.9074 −142.0994 Mirror 4 (25) A(4)204.7447 C-4 reflecting  80.2169 Image Image Distance = 39.9998  2.0029inf. APERTURE DATA Diameter Decenter Aperture Shape X Y X Y Rotation C-1Circle (obsc.) 25.069 Circle 6.000 6.000 C-2 Circle (obsc.) 76.190Circle 34.000 34.000 C-3 Circle (obsc.) 315.840 Circle 90.000 90.000 C-4Circle (obsc.) 388.014 Circle 100.000 100.000 Aspheric Constants$Z = {\frac{({curv})Y^{2}}{1 + \left\lbrack {1\left( {1 + K} \right)({curv})^{2}Y^{2}} \right\rbrack^{\frac{1}{2}}} + {(A)Y^{4}} + {(B)Y^{6}} + {(C)Y^{8}} + {(D)Y^{10}} + {(E)Y^{12}} + {(F)Y^{14}} + {(G)Y^{16}} + {(H)Y^{18}} + {(J)Y^{20}}}$K A B C D aspheric curv E F G H J A(1) 0.01632142 0.721125 −1.13241E−06−7.44173E−10 −1.20959E−13 1.82841E−16 5.01736E−33 2.59205E−340.00000E+00 0.00000E+00 0.00000E+00 A(2) 0.01249319 0.374720–−1.34649E−07 −2.20696E−11 −3.87070E−15 −5.51394E−19 7.61820E−23−4.74274E−26 0.00000E+00 0.00000E+00 0.00000E+00 A(3) −0.0016322−8.138119– 3.08966E−10 8.83050E−14 1.52159E−20 1.03323E−23 8.43173E−292.01064E−33 0.00000E+00 0.00000E+00 0.00000E+00 A(4) 0.00220115 1.2434854.66665E−10 −4.05558E−15 4.03013E−20 −5.94690E−25 6.74937E−30−3.83976E−35 0.00000E+00 0.00000E+00 0.00000E+00 AT USED CONJUGATES:REDUCTION = OBJECT DIST = TOTAL TRACK = IMAGE DIST = OAL = −0.01001684.0346 2000.0000 39.9998 275.9656

TABLE 2 Optical Data for Objective of FIGS. 2A/2B Curvature ApertureElement Radius Diameter (Ref. Symbol) Front Back Thickness Front BackGlass Object inf. 1533.8845 Mirror 1 (213) A(1) −447.4711 C-1 reflectingMirror 2 (217) A(2) 558.0315 C-2 reflecting Mirror 3 (245) A(3) −60.5605C-3 reflecting Mirror 4 (249) A(4) 376.0924 C-4 reflecting Mirror 5(221) A(5) −130.5321 C-5 reflecting APERTURE STOP 748.0479 −135.0000Mirror 6 (225) A(6) 265.5321 C-6 reflecting Image Distance = 40.0232166.8325 Image inf. 2.0046 APERTURE DATA Diameter Decenter ApertureShape X Y X Y Rotation C-1 Circle (obsc.) 29.950 Circle 6.000 6.000 C-2Circle (obsc.) 432.760 Circle 90.000 90.000 C-3 Circle (obsc.) 115.248Circle 10.000 10.000 C-4 Circle (obsc.) 136.401 Circle 60.000 60.000 C-5Circle (obsc.) 748.249 Circle 200.000 200.000 C-6 Circle (obsc.) 748.006Circle 240.000 240.000 Aspheric Constants aspheric curv K A B C D A(1)0.01462135 4.236799 0.00000E+00 −2.34672E−10 2.25315E−13 0.00000E+00A(2) 0.00215389 0.031898 0.00000E+00 1.71983E−16 4.27637E−21 0.00000E+00A(3) −0.00076244 381.118675 0.00000E+00 −2.25582E−12 −7.14313E−160.00000E+00 A(4) 0.00849256 0.414914 0.00000E+00 1.39628E−13−3.22627E−17 0.00000E+00 A(5) −0.00146641 −0.715112 0.00000E+00−2.04954E−16 −6.04643E−22 0.00000E+00 A(6) 0.00185791 −1.1716360.00000E+00 −1.34911E−15 1.97533E−21 0.00000E+00 AT USED CONJUGATES:REDUCTION = OBJECT DIST = TOTAL TRACK = IMAGE DIST = OAL = 0.01001533.8845 2000.0000 40.0232 426.0923

TABLE 3 Optical Data for Objective of FIGS. 3A/3B Curvature ApertureElement Radius Diameter (Ref. Symbol) Front Back Thickness Front BackGlass Object inf. 1954.1364 Mirror 1 (313) A(1) −450.8028 C-1 reflectingMirror 2 (317) A(2) 538.6037 C-2 reflecting Mirror 3 (345) A(3) −68.8878C-3 reflecting Mirror 4 (349) A(4) 375.9476 C-4 reflecting Mirror 5(321) A(5) −134.5548 C-5 reflecting APERTURE STOP 759.6775 −135.0000Mirror 6 (325) A(6) 269.5548 C-6 reflecting Image Distance = 40.0005166.7569 Image inf. 2.0027 Diameter Decenter Aperture Shape X Y X YRotation C-1 Circle (obsc.) 36.788 Circle 4.000 4.000 C-2 Circle (obsc.)550.616 Circle 80.000 80.000 C-3 Circle (obsc.) 126.324 Circle 4.0004.000 C-4 Circle (obsc.) 156.779 Circle 40.000 40.000 C-5 Circle (obsc.)760.748 Circle 200.000 200.000 C-6 Circle (obsc.) 759.241 Circle 200.000200.000 Aspheric Constants aspheric curv K/E A/F B/G C/H D/J A(1)0.01453296 3.993966 −1.25979E−07 −2.40984E−10 −2.22973E−13 −1.92806E−160.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00A(2) 0.00214496 −0.072178 9.97447E−11 5.58371E−16 2.94983E−212.11781E−27 1.14313E−31 1.09251E−37 0.00000E+00 0.00000E+00 0.00000E+00A(3) −0.00095338 177.846664 −4.27020E−08 3.95468E−12 3.32517E−20−6.96347E−20 1.24958E−24 9.52941E−28 0.00000E+00 0.00000E+00 0.00000E+00A(4) 0.00808626 0.279920 5.46076E−09 3.59983E−13 5.29416E−18−6.95655E−23 1.93949E−25 2.44723E−30 0.00000E+00 0.00000E+00 0.00000E+00A(5) −0.00151095 −0.696060 0.00000E+00 −3.66210E−16 −3.54668E−22−1.33788E−27 −2.47308E−33 −1.25578E−38 0.00000E+00 0.00000E+000.00000E+00 A(6) 0.00185048 −1.256318 −1.93114E−11 −1.38066E−152.59583E−21 −5.18058E−27 7.48520E−33 6.54710E−39 0.00000E+00 0.00000E+000.00000E+00 AT USED CONJUGATES: REDUCTION = OBJECT DIST = TOTAL TRACK =IMAGE DIST = OAL = 0.0100 1954.1364 2388.9976 40.0005 394.8606

1. A projection exposure apparatus comprising: an illuminating system toilluminate a drivable micromirror array and an objective, which projectssaid drivable micromirror array onto photosensitive substrate; whereinsaid objective comprises mirrors which are arranged coaxial with respectto a common optical axis and at least two partial objectives with anintermediate image plane between said at least two partial objectives,wherein said objective has an imaging scale ratio of greater than 20:1and each of said at least two partial objectives has an imaging scaleratio greater than 1:1.
 2. The projection exposure apparatus accordingto claim 1, wherein said objective is a catoptric objective.
 3. Theprojection exposure apparatus according to claim 1, wherein saidobjective has a numerical aperture at said substrate greater than 0.1.4. The projection exposure apparatus according to claim 1, wherein saidpartial objective between said drivable micromirror array and saidintermediate image has an imaging scale ratio which is substantiallygreater by comparison with said partial objective between intermediateimage and said photosensitive substrate.
 5. The projection exposureapparatus according to claim 1, wherein said objective is an objectivewith pupil obscuration.
 6. The projection exposure apparatus accordingto claim 1, wherein said objective comprises mirrors being coated withreflecting layers which are adapted to reflect two mutually separatedoperating wavelengths.
 7. The projection exposure apparatus according toclaim 1, wherein an axial spacing of said drivable micromirror arrayfrom said photosensitive substrate is less than or equal to 3000 mm. 8.The projection exposure apparatus according to claim 1, wherein saiddrivable micromirror array is arranged not centered relative to a commonoptical axis of said objective.
 9. The projection exposure apparatusaccording to claim 8, wherein said drivable micromirror array isarranged outside said optical axis.
 10. The projection exposureapparatus according to claim 1, wherein said illuminating systemcomprises a grazing-incidence mirror for coupling in the illuminatinglight towards said drivable micromirror array.
 11. The projectionexposure apparatus according to claim 10, wherein said grazing-incidencemirror has an axial spacing from said drivable micromirror array whichis greater than 20% of an axial spacing of said drivable micromirrorarray from said photosensitive substrate.
 12. A projection exposureapparatus comprising: an illuminating system to illuminate a drivablemicromirror array and an objective, which projects said drivablemircromirror array onto a photosensitive substrate; wherein saidobjective is catoptric objective with an imaging scale ratio of greaterthan 20:1 and includes at least two partial objectives with anintermediate image plane between said at least two partial objectivesand each of said at least two partial objectives has an imaging scaleratio greater than 1:1.
 13. The projection exposure apparatus accordingto claim 12, wherein said objective has a numerical aperture at saidsubstrate greater than 0.1.
 14. A projection exposure apparatuscomprising: an illuminating system to illuminate a drivable micromirrorarray and an objective, which projects said drivable micromirror arrayonto photosensitive substrate; wherein said objective comprises at leasttwo partial objectives with an intermediate image plane between said atleast two partial objectives and each of said at least two partialobjectives has an imaging scale ratio greater than 1:1, the objectivehaving an image scale ratio of greater than 20:1.
 15. The projectionexposure apparatus according to claim 14, wherein said partial objectivebetween said drivable micromirror array and said intermediate image hasan imaging scale ration which is substantially greater by comparisonwith said partial objective between said intermediate image and saidphotosensitive substrate.
 16. A projection exposure apparatuscomprising: an illuminating system to illuminate a drivable micromirrorarray and an objective, which projects said drivable micromirror arrayonto a photosensitive substrate; wherein said objective is an objectivewith pupil obscuration and at least two partial objectives with anintermediate image plane between said at least two partial objectives,wherein said objective has an imaging scale ratio of greater than 20:1and each of said at least two partial objectives has an imaging scaleratio greater than 1:1.
 17. A projection exposure apparatus comprising:an illuminating system to illuminate a drivable micromirror array and anobjective, which projects said drivable micromirror array onto aphotosensitive substrate; wherein said objective consists of mirrorsbeing coated with reflecting layers which are adapted to reflect twomutually separated operating wavelengths and at least two partialobjectives with an intermediate image plane between said at least twopartial objectives, wherein said objective has an imaging scale ratio ofgreater than 20:1 and each of said at least two partial objectives hasan imaging scale ratio greater than 1:1.